In recent years, inkjet recording methods have been applied in a variety of graphic arts fields such as photography, various kinds of printing, marking and color filters, since it can form images easily at low cost. Particularly, it is also possible to obtain image quality comparable to silver halide photography, by utilizing a recording apparatus which ejects and controls tiny ink dots, ink improved in the color reproduction range, durability and ejection suitability, and a specifically appropriate sheet which exhibits greatly improved ink absorption property, the coloring property of colorants, and surface glossiness. Improvement of image quality at this time has been achieved only by the complete set of various components of an apparatus, the ink and specifically appropriate sheets.
However, in an inkjet method requiring a specifically appropriate sheet, there are problems of limitation and increased cost of the recording medium. Therefore, many attempts have been made to record by means of an inkjet method onto a transferring medium different from the specifically appropriate sheets. Specific examples include a phase transition inkjet method which utilizes wax ink which is solid at room temperature, a solvent type inkjet method which utilizes rapid-drying ink mainly comprised of an organic solvent, and a ultraviolet (UV) inkjet method in which ink is cross-linked by UV light after recording.
Among these, the UV inkjet method has many advantages compared to the solvent type inkjet method resulting in its proliferation in recent years, and of such UV rays actinic ray curable inkjet ink is disclosed in Japanese Patent Publication No. 5-54667, JP-A No. 6-200204 (hereinafter, JP-A refers to Japanese Patent Publication Open to Public Inspection) and WO No. 2000-504778.
Actinic ray curable ink, which utilizes a compound as a vehicle curable by actinic rays such as UV rays, is superior in rapid drying characteristics, requires no heat drying process, also has advantages of no environmental contamination and exhibits greater safety due to being solvent free. Further, as polymerizing compounds used as a vehicle, widely utilized have been radical polymerizing types, which have a rapid curing rate, of which there are many kinds, however, a cation polymerizing compound has also been recently utilized, due to advantages such as it being only a little effected by oxygen, an effect which is unavoidable in radical polymerization, and of minimum shrinkage during curing.
A cation polymerizing compound includes typically various kinds of epoxy resins having an oxirane ring, and also reported (for example in patent literature 1–4) are compounds having an oxetane ring (hereinafter, referred to as “an oxetane compound”).
However, the above-described cation polymerizing compounds are slow in curing rate and often result in inadequate curing. Further improvements have been sought in view of poor storage stability under high temperature environments. Further, pointed out is a concern of safety such as possible bad effects on the human body.
Patent Literature 1
Japanese Patent No. 2679586 (Scope of Claims)
Patent Literature 2
JP-A No. 8-143806 (Scope of Claims)
Patent Literature 3
JP-A No. 2002-317139 (Scope of Claims)
Patent Literature 4
JP-A No. 2002-188025 (Scope of Claims)